Intraocular lenses (IOLs) are routinely implanted in patients' eyes during cataract surgery to replace the natural crystalline lens or to compensate for the lost optical power. The terms “intraocular lens” and its abbreviation IOL are used interchangeably herein to describe lenses that are implanted into the interior of an eye to either replace the natural lens or to otherwise augment vision regardless of whether or not the natural lens is removed.
Traditional IOLs are spherical, meaning the posterior surface is curved. However, aspheric IOLs have an aspheric surface to correct corneal spherical aberration. Toric IOLs have a toric surface to correct or mitigate corneal astigmatism over a range of diopters.